Method for edge crimping thermoplastic yarns



April 20, 1965 w. P. WARTHEN 3, 78,

METHOD FOR EDGE CRIMPING THERMOPLASTIC YARNS Filed Oct. 10, 1962 3 Sheets-Sheet l INVENTOR. WILLIAM P. WARTHEN ATTORNEY April 20, 1965 p, w EN 3,178,795

METHOD FOR EDGE CRIMPING THERMOPLASTIC YARNS Filed 001;. lO, 1962 3 Sheets-Sheet 2 INVENTOR. WILLIAM P. WARTHEN AT RNEY April 20, 1965 w. P. WARTHEN METHOD 'FOR EDGE CRIMPING THERMOPLASTIC YARNS Filed 001;. 10, 1962 3 Sheets-Sheet 3 INVENTOR.

N M m /Y A w. m P ,,T m M u H W Y FM crimped by a process known as edge crimping.

United States Patent 3,178,795 METHOD FOR EDGE CRDVIPING THERMO- PLASTIC YARNS William P. War-then, Spartanburg, S.C., assiguor to Deering Milliken Research Corporation, Spartanburg, S.C.,

a corporation of Delaware Filed 0st. 10, 1962, Ser. No. 229,563 Claims. (Cl. 28-72) This invention relates to a process for crimping thermo plastic filaments and to apparatus for carrying out the process.

Continuous filament thermoplastic yarns are comngonly n an edge crimping process, a thermoplastic yarn heated to an elevated temperature is drawn over a sharply angu lar body or deforming edge whereby the yarn is stressed in a manner such that the filament or filaments comprising the yarn assume a highly convoluted configuration.

This method of crimping continuous filament thermoplastic yarns is highly desirable for the reason that yarns crimped by this method normally have little or no tendency to twist and can readily be employed single ply.

Edge crimping also differs from most other methods of crimping thermoplastic yarns in that the elastic nature of a yarn processed in this manner is only partially apparent following passage of the yarn about the deforming edge, and a heat treatment is necessary to develop its full elastic nature.

Edge crimped yarn crimping apparatus have employed various edges for effecting the crimp. The crimping edges have been edges such as stationary edges, reciprocating edges and rotating edges such as that provided by the inner surface of a rotating ring or tube. A fairly recent innovation, however, in the field of edge crimping apparatus is the use of a traveling length of the filament itself as a crimping member. When a filament crimping member is employed, the filament to be crimped is passed in a heated condition and under tension over and in contact with a portion of the same filament traveling across the path of the filament to be crimped so that the latter filament is sent over the aforesaid traveling filament at an angle thereby becoming potentially crimpable.

Certain problems have developed, however, in the use of a filament as the crimping member for a continuous thermoplastic filament. Some of the problems experienced in using a filament medium are riding, binding and breaking of the filament to be crimped on the filament crimping member. The term riding as used herein is meant to define a traversing movement of the filament to be crimped on the filament crimping member and more specifically a traversing movement of the filament to be crimped in the direction of movement of the filament crimping member.

Another common problem is failure of the filament to be crimped to receive sufiicient contact with the filament crimping member as to impart sufficient crimps per inch necessary for a commercial product. 7

It is therefore an object of this invention to provide a method for crimping thermoplastic continuous filaments in a system employing atraveling filament as a crimping member in a manner such that the crimped filament has that number of crimps per inch which renders the filament a commercial product.

3,178,795 Patented Apr. 20, 1%65 It is another object of this invention to provide a method for crimping a continuous thermoplastic filament in a system employing a moving filament as a crimping member in a manner such that the thermoplastic continuous filament to receive the crimp does not ride, bind or break on the filament crimping member.

It is still another object of this invention to provide apparatus of the type employing a moving fialment as a crimping member for crimping continuous thermoplastic filaments, the apparatus being designed so as to prevent the filaments to be crimped from riding, binding or breaking and also designed so as to allow the filament to be crimped to have suificient contact with the running filament crimping member as to give the filament to be crimped a full degree of crimp.

In accordance with this invention, it has now been discovered that a running length of thermoplastic filament may be crimped in an improved manner by softening said yarn under the influence of heat and immediately wrapping said yarn around a single length of itself, the wrap covering not less than a 360 turn. It should be understood that the crimping operation may be carried out once or a plurality of times, that is to say, the running length of yarn may be softened under the influence of heat and immediately wrapped about a plurality of separate lengths of itself, each wrap covering not less than a 360 turn about a single length. The improved crimp is also effected by means of a process and apparatus which prevent riding, binding and breaking of the filament. Riding, binding and breaking of the filament are prevented by progressively passing said filament through an angle about a small radius generally convexly curved surface formed by a preceding linearly progressed segment of said filament moving transversely across the direction of movement of the portion of said filament passing through said angle, said preceding linearly progressed segment of said filament assuming a V-shaped path and said filament to be crimped being bent through an angle of at least 360 over said linearly progressed segment. The V-shaped path of the filament crimping member is an inherent feature of a process wherein the filament to be crimped is under less tension than the preceding linearly progressed segment. The V-shaped path of the filament crimping member is maintained without the filament to becrimped riding or binding and thereby destroying the V-shaped configuration by passing that linearly progressed segment forming the filament crimping edge through entrance and exit spaced-apart yarn guides disposed on opposite'sides of the apex of said V-shaped path, said exit yarn guide being spaced upstream from said entrance yarn guide with respect to the direction of flow of the yarn to be crimped.

The apparatus and process of this invention have solved the problem of poor crimping which was a detrimental feature in heretofore known processes for crimping a yarn by employing a continuous moving yarn as a crimping member. In order to set forth the improvement of this invention, it is necessary to define the term crimping. A thermoplastic monofilament treated by means of an edge crimping process will assume a helical configuration. A helical configurationmay be measured in terms of amplitude and frequency. When an edge crimped yarn is under substantially no tension, frequency measurev yarn crimping apparatusof this inventiona 1 .3 and, 4. The yarnadvancing' rneans. a're actuatedby a" Yarn advancing means .3 has a small 17 'diameterf section f 4. has. .a :smallidia meter section ,7 and. a. large diameter;

Y m d n nsl an e passing from tensioningjdeyice- 2 ispassed', a outsthe.

1 3 "and 4, respectively, a (plurality "oft e ments may be. ignored andcrimp measurements for the is then passed overv guiderolls 9 through entrance guide monofilament may be based on amplitude alone. A'mpli- It) .and' eXit guide 11 to formthe crimping 860E011. 12.. tude determination of edge crimped monofilajment yarns" l ,The yarn is then passedover large diameter sections is made by cutting the crimped 'monofilament into short ,6jand8 ofyarn advancing means 3 and .4, respectively, a lengths and placing the short lengths on a gridded screen 1 .plurality. of times and thenover hot'roll 13.. The cnmpcalibrated in millimeters; Each'of these short lengths'is ing member, is maintained under the desired tension by found to produce a coil of more or less circularsize. 1 selecting the proper ratio of surface speeds' between I The diameter of the coils may then be'measured by means 7 small roll section 5- and large. roll section 6 of yarn ad' or the gridded screen. Useful coilrsize or crimp size is vancing means 3. The surface speed of the large roll usually considered to be in the range of 0.4v to 1.0 10 section 6 should'be 1.5% Qto 4% fasteir than the surface mm. In a process employing a segment "of yarnas a speed of smallroll section 5. Hot roll 13 may be heated deforming edge, the desired, coil'size range mayonly be by'a'ny c'onvenientmeans suchas, forlinstance, electricity, obtained by contacting'the yarn to be crimped. with the; liquid organic heat transfer mediums and the like. .The yarn deforming edge-for at least one full turn or 360. 'surface'speedofrhot roll 1 3'isiapproxirnately equal to or It has also been'found that in orderto obtainthe desired v slightly in excess of 'thatfof' large roll section 6 of yarn coil size range that'the speed of the yarn receiving a advancing'me'ans .31 Yarn passing from-hot. roll 13 is crimp should preferably be no greater than '40 yards thenwrapped about'crimping segmentslz througha'wrap per minute. -Where the r'ate of yarn travel is in excess of i of at least onefull turn orf3.6 0. The yarn coming off 40 yards per minute; it is beneficial tocombin'ea cooling hot 'roll 13 and beingwrappedabout crimping segment device with the'crimping apparatus of thisinvention. The 12 is under'less tension thanfc'rimping'segment 12 in that cooling device which may; be a device such as,',for; in theyarn coming fromhot roll 13 has been 'overfed' with V stance,"-a heat sink of a metal having high thermal; con-. respect 'to *cold roll-[14. which has asurface {speed a ductivity, an air 'jet, a water pad or the" like, should. be proximately equal toor slightly lessthanthat of'hot roll placed irnme'diately'behind'the yarnfcrimping..edge so. as I: 13'; and overfed with respect to yarn advancing meansto cool the crimpe'dyarn as soon as possible thereby pre-; 15 and 16, yarn advancing eans 15 having a i surface venting-tension on the crimped yarn' from.removingfthe v speed" of from -15 to' less thanthesurface speed. newly'formed crimp. j j of'sections'6 and .8 of advancing rolls 3 and 4.*Abetter The filament to' be crimped, according to themethod set understanding of the crimping operation which takes forth inthis invention should bejatherrnoplastic fil a I place in. wrapping the heatedyarnabout the crimping ment and pr'eferably ,aythermoplasti'c monofilament; The segmentlz may be hadflfrom FIGURES, land 3 of they denier size maybe. frornjljde'nier to 180 denier. Specific, drawing's. FIGURE Z' clearly illustrates the vfshaped thermoplastic polymers whichare suitable for nsein this: configuration of the crimping segment lzfwhich has been inventio'mare polymers such as; for instance, Jpolyhexaformc'd'bY p ge-cre m about guide mu; 9. hro gh methylene. 'sebacami de,- polyhexamethylene adipamide entrancefguide Q10 and e'xitguide 11. 'Theyarn to be polycaprolacturn and the like. The thermoplastic'poly 5 crirnped which passes-from. hot roll' .13, .which is shown mers employed in this invention should .be heated prior; in phantom view, is wrappedinfexcess or, 360. about tobeing subjected to 1 the crimping... medium" to te mcrimping segment-12 .before. being passed .over coldroll peratures of from greater than. 180 F. to'a point .at 14.; The staggered positioning of entrance yarn guide. least;80?-F. below'the melting point Of the specific thermoe i 10 ty n d l' may t' e GU 3. plastic polymenbeing employed.- Tensions." appliedf-ltov 40- I'II'FIGURE Bijcrim'pihg segment 12 is formed by pasthe thermoplastic materials in this invention dur'ing :and Q sage of yarnbetweenentranCe yarn guide"; 10 and exit subsequent to the crimpingoperatiomwillvary accord yarn"guide'i'11. (Exit yarn guide 11 is position ed uping to the specific theri'nopla'sticv materials and {specific Stream frbihientrance yard-gui d 10-. Withr spec ot e temperatures employeqh Tensions applied to'a' lS'd'enier direction. of: flow of the yarnrtelbe crimped which is.

nylon mono filamentfor instance, at;the point of 'wrap. about the crimping: segment, are frorn ofi gram to 3.5.

illustratedas p'assingovetf crimping segment 12 inl a'wrap; of atle'ast 3609. Returning to :FI GUR E -I, thefyarng.

grams at a temperature 'rangeof from 180 ,R'to 45 0f? coming off crimping segment 12 isthen passed over cold- The tensions; subsequent toerimping ppe'ratiori must; roll 14 and "then 'aboutfyarnradvancing rollsols and 16; not be great enough tgiremove. sub'stantiaL amounts; of; f p r v P T .surface Speed of yar d a s;

usefulQcrimp applied to the yarn. rolls 15 andil6- is-leSsrthan the surfacespeed 0f hot roll A better.understanding.ofi the invention may: be hadg 1 5116 co drolly 14 The? reduced vsurfac espeedof.yarn from a discussioniof; the drawings Whichare as follows; 1 advancing rolls "15. and {I6 reducetheitension J'n'thenevvly FIGUREI is a diagrammatic viewjof onetype of; "crimped yarnf and thereby insure retention of maxiyarncrimping apparatus of this invention." mum amounts. of crimpi'. The' .yarn* passing from; yarn FIGURES 2 and 3. are. expandedv fragmentaryrviewsi' V of a'portion of the apparatus shownin EIGURE, 1 P k g 1 L] a i x FIGURESA;and5jare further "arrangementsgf r ac- It should 'be under'stoodthat the yarn. to be crimped o p ng thepurposeslofj this inventiong. V, M g I g FIGURE6 isfa' diagrammaticviewof another typeof than'onejfullfwrap'and also may. be wrapped about a 1 nrounn '71; an expandedjfragmentary. view ra e '60 tion of the apparatus shown in FIGllREfi. 1

. FIGURE ,1', yarn is' 'fed from. al'supply, bobbin 1 v lessthan 21 360 3, tum; .The, aforementionedfeatures are,

'advancingrolls 15. and 16 is then woundon take-up ma be wrappedmboutgthe cri mping; segment for more a plurality .Ofcrimping segmentsi'each wrap covering not;

clearly" illustrated aim-FIGURES 4 and 5 respectively. In :EI GURE .4, v a crimping segment; 22 'is';;formed by; pas--- throughatensio'riing device 2'ontoyarn advancingme {sage of yarnbetween'entranc nf id zg it suitable driving; means, ;all of. the yarn yadyaiicing rneam' 2 7 Sand alargeidiametei'. section 6.; Yarn advancing'r'neans r c rimpirigv segmentsf 32z' V 7 "3 1; is; turned :aboute guidefrollsj and; 4 -"rotate' in:.,.uni'son Yarn 5' for. the formation of additional section 8; j The small 'and larg'e' diameter sectionsfof bothas to lie: in? position smalli'diametersections 5 and 7 of yarn jad vancing means;

.Ya'rn guide-"2 1. Q'Ihe yarn to, be crirnpedis thenpassed.

. about. crimpinggsegmentgzz for a; plurality of wraps... of the, apparatu s'being'. synchronized by the: driving ni'eans i.Asp rag sfi nnl y ngia p u a ty- {crimping segments: "ii slfill ustr'ated in FIGURES.-iYarnfiS' -passed."between entrance yarn guidesfillrandiexit yarn guides 31 toform Yarn ,leaving exit yarn guides;

To facilitate ease of threading the apparatus at the start of crimping operations, another form of apparatus may be employed which is illustrated in FIGURE 6. In FIGURE 6 yarn is passed from supply bobbin 41 to yarn advancing means 42 and 43. The yarn advancing means are actuated by a suitable driving means, all of the yarn advancing means of the apparatus being synchronized by the driving means. Yarn advancing means 42 is divided into three sections which are an intermediate diameter section 44, a large diameter section 45 and a small diameter section 46. Yarn advancing means 43 is also divided into three sections which are an intermediate diameter section 47, a large diameter section 48 and a small diameter section 49. Both yarn advancing means 42 and 43 are unitary devices, that is to say, the three sections composing each of the two rolls rotate in unison. The devices 42 and 43 are also driven in such manner that their three respective sections have the same surface speed. Yarn from supply package 41 is wrapped about intermediate diameter sections 44 and 47 of yarn advancing means 42 and 43, respectively for a plurality of wraps and is then brought about roller guide members 50 through entrance guide 51 and exit yarn guide 52 to form crimping segment 53. The crimping segment 53 is shown in raised position, the raised position being obtained by the ability of roller guides 50 to function as hinges thereby providing a swinging arm member. When crimping segment 53 is in use, it is lowered into the position shown in the phantom view. After formation of crimping member 53, the yarn is returned over roller guides 50 to large roll sections 45 and 48 of yarn advancing means 42 and 43, respectively.

' The yarn is wrapped a plurality of times about large diameter sections 45 and 48 and then passed over hot roll 54. The surface speed of the large diameter section 45 should be 1.5 to 4% faster than the surface speed of intermediate diameter section 44. Hot roll 54 may be heated by any convenient means such as, for instance, electricity, organic heat transfer mediums and the like. The surface speed of hot roll 54 is approximately equal to or slightly in excess of that of large roll section 45. After passage over hot roll 54, the yarn is wrapped about crimping member 53 through a wrap of at least 360. A better understanding of the crimping operation which takes place at this point may be had from a discussion of the expanded fragmentary view of the crimping edge portion of the apparatus shown in FIG- URE 7. In FIGURE 7 yarn is passed over entrance yarn guide 51 to exit yarn guide 52 to form crimping segment 53. Yarn guides 51 and 52 are adjustably carried by arm member 58. Exit yarn guide 52 is positioned upstream from entrance yarn guide 51 with respect to the direction of flow of the yarn to be crimped. The yarn to be crimped is wrapped about crimping segment 53 for at least one full turn or 360. The staggered relationship of exit yarn guide 52 to entrance yarn guide 51 prevents the filament to be crimped from riding up the crimping segment 53 to a position adjacent exit I yarn guide 52. Returning to FIGURE 6, crimping segment 53 retains its proper V-shaped configuration by reason of the fact that it is under greater tension than the yarn to be crimped.

The yarn coming off hot roll 54 and being wrapped about crimping segment 53 is under less tension than crimping section 53 in that the yarn forming crimping section 53 has been underfed with respect to large roll section 45 of yarn advancing means 42 by an amount to obtainthe desired tension. The yarn coming off hot r611 54 and being wrapped about crimping segment 53 is under less tension than crimping segment 53 in that the yarn coming from hot roll 54 has been sufficiently overfed with respect to cold roll 55 and oil roll 56, each of which have a surface speed approximately equal to or slightly less than that of hot roll 54, and suificiently overfed I with respect to small diametersections 46 and 49 of yarn advancing means 42 and 43, respectively, small diameter sections 46 and 49 having surface speeds of from 15% to 35% less than the surface speed of large roll sections 45 and 48 of yarn advancing means 42 and 43, respectively. Passage of the yarn about small diameter sections of yarn advancing means 42 and 43 decreases the tension on the crimped yarn and thereby diminishes the possibility of removing the newly set crimp from the yarn. The yarn is then taken off yarn advancing means 42 and 43 and wound on take-up package 57.

The apparatus and process of this invention have solved the riding, binding and breaking problem and the problem of formation of useful crimp size in the yarn by passage about the yarn itself. The riding of the yarn to be crimped has been solved by two novel improvements, the first of which is the positioning of the guides which properly position the crimping segment and the second of which is the regulation of the crimping segment under a greater tension than that of the yarn to be crimped. The maintenance of crimping segment tension at higher values than that of the yarn to be crimped is obtained by proper regulation of the surface speeds of the yarn advancing means. The surface speeds of the yarn advancing means have been discussed in conjunction with the explanation of FIGURES l and 6. The formation of useful crimp size in the crimping of yarn by passage about the yarn itself is obtained by passage of the yarn about itself in a wrap of not less than 360.

What is claimed is:

l. The method of edge crimping a running length of thermoplastic yarn comprising softening said yarn under the influence of heat andimmediately wrapping said yarn about a single length of itself, the wrap covering not less than a 360 turn.

2. The method of edge crimping a running length of thermoplastic yarn comprising softening said yarn under the influence of heat, immediately wrapping said yarn around a single length of itself, the Wrap covering not less than a 360 turn and then drawing said running length of yarn out of the wrapped configuration and cooling.

3. The method of edge crimping a running length of thermoplastic yarn comprising softening said yarn under the influence of heat, immediately wrapping, a wrap covering not less than a 360 turn, said softened yarn sequentially about a plurality of single lengths of itself and then drawing said running length of yarn out of the wrapped configuration and cooling.

4. In a yarn edge crimping process wherein a running length of thermoplastic filament to be crimped is heat softened and progressively passed through a turn of at least 360 by wrapping said filament about a convexly curved surface formed by a preceding linearly progressed segment of said filament passing transversely across the direction of movement of the filament proceeding through the turn, the improvement comprising maintaining said running length of filament to be crimped at a lesser tension than said preceding linearly progressed segment.

5. A yarn crimping process according to claim 4 wherein the filament which is passing transversely across the direction of movement of the portion of said filament being crimped, and the filament to be crimped, are linearly progressed at a rate no greater than about 40 yards per minute.

6. A yarn crimping process according to claim 4 wherein the thermoplastic filament to be crimped has a denier size ranging from about 15 to about 180.

7. A yarn crimping process according to claim 6 wherein the thermoplastic filament is heated to temperatures of to greater than about 180 F. to a point at least F. below the melting point of the specific thermoplastic polymer constituting the filament.

8. A yarn crimping process according to claim 7 wherein the thermoplastic filament is nylon.

31783795 f 7 l 2 t 9. A yarn crimping process eccerding tq clairn'8 where-L filment being erimped,',each wrap about the individual A tensions maintained-upon qthe filament range frem filament, cbn'stitptingfjnotless than one ,full turn; 33 g5 ra gg s gn gg g t mrer m j Reie'renee's Cited By we Examiner 10; "Ajarn' crimping pr oeees aecorgiing to claim 4 5 1 1 K Z T S' NI j wherein' a: heat; softenedfthermoplastic filamentfto be 3 0 5 23 5/ 9 1 crimped is' prqgressively wrgpped about a plurality. of 1 "1 3 5/ g ---t 2 individual angfsi n'gl'e lengths .of preceding linearly pro r STEIN,;Pfimary Exdrfii rie r. I gressed segments of said filamen t passing transversely RUSSELL C, MADER, DONALD.W. PARKER, across the direction of movement of the portion 'of, said v 7 I I E a iner 

2. THE METHOD OF EDGE CRIMPING A RUNNING LENGTH OF THERMOPLASTIC YARN COMPRISING SOFTENING SAID YARN UNDER THE INFLUDNCE OF HEAT, IMMEDIATELY WRAPPING SAID YARN AROUND A SINGLE LENGTH OF ITSELF, THE WRAP COVERING NOT LESS THAN A 360* TURN AN THEN DRAWING SAID RUNNING LENGTH OF YARN OUT OF THE WRAPPED CONFIGURATION AND COOLING. 